This invention relates to hand exercisers of the type which the user operates by opening and closing his hand against the pull of an elastic tensioning mechanism.
The utility of a hand exerciser is directly related to its capability or efficiency in restoring deteriorated hand and forearm muscles and tendons. The degree and nature of such deterioration which controls the prescribed treatment varies widely from patient to patient and continually changes for each patient during the course of successful treatment. The pull or tension developed by the exerciser mechanism must therefore be changeable by the user or his doctor over a wide range of values and in many increments as the patient improves. For example, a patient recovering from third degree burns on a hand may be capable of exerting only 0.1 to 0.3 ounce of muscular tension with that hand at the outset of treatment and 2.5 to 3 pounds of pull when treatment is complete. In such a case the patient's rate of recovery may require as many as 25 to 30 tension adjustments in the exerciser.
Another measure of the utility of hand exercisers is their capability of uniformly applying a yielding force to their user's fingers while permitting natural movements of the hand as it opens and closes. Proper restoration of hand and arm muscles and tendons requires such natural movements of all parts of the hand. Prior devices with fixed finger grip members have tended to restrain or inhibit the desired curling movement of the hand as it closes, and pivot action exercisers nonuniformly apply a tension force across the hand at any one instant. Such deficiencies in present exercisers become even more significant with severely damaged or deteriorated hands at the beginning of therapeutic treatment when digital movement is weak and small.
A general object of this invention is the provision of a hand exerciser of simple inexpensive construction which is easily adjusted to provide yieldable forces having an extremely wide range of values.
A further object is the provision of a hand exerciser which applies a tension force uniformly to all fingers during opening and closing of the hand.
Still another object is the provision of such an exerciser which facilitates natural movements of the hand as it closes against the applied tension force.